Ajax and rich Internet applications are today's big development challenges. But what about tomorrow?

Ajax has dramatically changed the lives of Web developers during the past two years, but the next two may be even more interesting. These developers—spurred by user expectations, rapidly evolving business models and ever-changing development processes—will need to do things they can't even imagine today. And how can a forward-thinking IT department or entrepreneur—who is so dependent on innovative software developers—prepare for that future?

To find out, we could have asked prominent Web developers to gaze into their crystal balls. Doing so, however, would have been dangerous: They'd have told us what the industry wanted to see rather than what we're likely to see.

Instead, we approached the tool builders. These technology experts—who run development tool companies and lead open-source projects—lie awake at night contemplating what's next. More importantly, the programming environments and frameworks that these visionaries create are the ones developers will use to build their applications. If these guys think a user or programmer need is inevitable, you can expect their next generation of Web development tools to answer the call.

We sat down with key toolmakers from Microsoft to Adobe, and from both proprietary companies and open-source projects, to learn their view of the future. And we spoke to the techies and designers, not the marketers. Their predictions address the next round of developer opportunities, problems—and consequences.

Jean-François Abramatic, chief product officer at ILOG, who also served as chairman of the W3C (currently he's on the W3C Advisory Board) and as a director of the Internet Corporation for Assigned Names and Numbers (ICANN)

Fair warning: Crystal ball gazing usually involves a murky date stamp. As Microsoft general manager for the .Net development platform, Scott Guthrie says, "We overestimate what will happen in the next two years and we dramatically underestimate what will happen in the next 10."